Refrigerating apparatus and method



Aug. 6, 1940. o. w. GREENE 2.210.031

I REFRIGERATING APPARATUS AND METHQD Filed Aug. 2 1936 4 Sheets-Sheet 1-%z.'$ ATTORNEYS 6, 1940- 'o. w. GREENE 2.210,031

, REFRIGERATING APPARATUS AND METHOD Filed Aug. 28, 1936 4 Sheets-Sheet2 .E i INVENTOR.

(Greene ATTORNEYS Aug. 6, 1940.

GREENE 2.210.031 I REFRIGERATING APPARATUS AND METHOD Filed Aug. 28,1936 INVENTOR.

reene -zi6 ATTORNEYS REFRIGERATING APPARATUS AND METHOD Filed Aug. 28,1936 4Sheets-$heet 4 LI X {170 140 j; I a I: l x i N All; a T170 26 X Il J1 I X :50 )id E I 1L5" E -.:z70 1/430 rm H:

Y -.Z70 123 J 140 INVENTOR. 0% WGrGcnc ATTORNEYS Patented Aug. 6, 1940UNITED STATES PATENT OFFICE Otto W. Greene, Elyria, Ohio, assignor toThe Pfaudler 00., Rochester, N. Y., a corporation of New YorkApplication August 28, 1936, Serial No. 98,332

14 Claims.

This invention relates to a method of and apparatus for refrigeration.An object of the invention is the provision of generally improved andmore satisfactory cooling apparatus of the above mentioned type.

Another object is the provision of cooling apparatus so designed andconstructed that the cooling fluid will be moved effectively through thepassageway or conduit in which it is placed,

Another object is the provision of a passageway or conduit for thecooling fluid, so designed and constructed that substantially the entireinner surface of such passageway or conduit will be kept continuouslycovered with unvaporized cooling liquid.

Still another object is the provision of a pas- I sageway or conduit forthe cooling fluid so designed as to have a cross sectional areaincreasing in the direction of flow of the fluid in rough proportion tothe increase in volume of the fluid caused by passage of part thereoffrom liquid phase to vapor phase.

Still another object is the provision of a passageway or conduit for thecooling fluid, so designed that any substantial bodies of liquid passingtherethrough will be atomized or broken up into a spray of particles atcertain points in the passageway.

A further object of the invention is the provision of cooling apparatusso constructed that it may be cleaned with great case so as to vbeespecially suitable for use in connection with food productsh wheresanitation is important.

A further object is the provision of cooling apparatus so designed thatexpansion and contraction stresses resulting from temperature changesmay be readily accommodated without causing leakage at joints or otherdamage to the A still further object is the provision of coolingapparatus so designed and constructed that it may be readily placedwithin a closed tank or container through a relatively small manhole.

My invention further contemplates a method or increasing the emciency ofa cooling coil by causing the refrigerant, particularly that portion ofthe refrigerant in liquid phase, to flow at high velocity in intimatecontact with the walls of the coil.

To these and other ends the invention resides in certain improvementsand combinations of parts, all as will be hereinafter more fullydescribed, the novel features being pointed out in the claims at thecadet the specification.

In the drawings:

Fig. 1 is an end view of a fragment of a tank equipped with one form ofcooling apparatus according to the present invention;

Fig. 2 is a section taken substantially on the line 2-2 of Fig. 1;

Fig. 3 is a vertical section taken longitudinally through the tank ofFig. 1;

Fig. 4 is a vertical section taken substantially on the line -4 of Fig.3;

Fig. 5 is a view of one form of conduit which may be used in the coolingapparatus;

Fig. 6 is a similar view of an alternative form of conduit;

Fig. 7 is a developed diagrammatic view of the conduits through whichthe cooling fluid flows, in one form of construction;

' Fig. 8 is'a vertical section through the header to which certain otherconduit sections are con nected, this section being taken substantiallyon the line 8-8 of Fig. 3, and

Fig. 9 is a vertical section through an alternative form of apparatus.

The same reference numerals throughout the several views indicate thesame parts.

The present invention may be embodied in apparatus of the surfacecooling type, providing a cooling surface over which the milk or otherliquid to be cooled may flow, such a construction being illustrated inFig. 9, or it may be embodied preferably in apparatus of the immersiontype, in which the conduits, passageways or coils carrying the coolingfluid are immersed in a body of the liquid to be cooled, which body ofliquid is held in a suitable tank or container. This preferred form ofconstruction is indicated in Figs. 1 to 8 inclusive, tmwhichreierencewill now be made.

The tank or container for holding the liquid to be cooled is indicatedin general at l 2, and may comprise an inner metallic wall l3 covered bya layer H of insulating material and an outer jacket I! of thin sheetmetal or other suitable material. A manhole cover l6 closes a manhole llof standard or usual size. Preferably, but not necessarily, the tank orcontainer is of generally cylindrical shape, with its axis arrangedapproximately horizontally, as shown, and the manhole is in one end wallof the tank.

Within this tank is an immersion cooling unit comprising a headersection 2| and a series 01' conduit sections 2| to 34 inclusive, formingloops or passes. The header section 20 may be straight, curved, or ofany other desired shape, but in the preferred form of the invention thisheader is formed of a tube bent to a somewhat elliptical outline asindicated in Figures 1, 4 and 8, with the ends of the tube joined toeach other at as by welding or the like. The partition 4| is preferablysecured in the tube, as by welding, adjacent the joint 40, and the inletis just to one side of this partition and the outlet just to the otherside thereof, so that the cooling fluid entering at the inlet must fiowaround the entire elliptical outline of the header before reaching theoutlet.

The conduit sections 2| to 34 inclusive may extend from the headersection 20 to a second header section, or they may simply be connectedto each other in pairs or formed integrally with each other so as toconstitute return bends or coil sections. For instance, as shown in Fig.6, two of the adjacent conduit sections 2| and 22 may be formedintegrally with each other or formed of two sections welded to eachother to provide. an approximately semi-circular connecting bend at theends of the sections 2| and 22 remote from the header 25. Such asemicircular return bend is quite satisfactory in many instances, butfor greatest efliciency within the cooling unit, and for leastresistance to flow of liquid past the cooling unit, it is preferred touse sharp angular connections instead of the semi-circular bends shownin Fig. 6. Such sharp angular connections are indicated in Figures 3 and5. Each two adjacent conduit sections 2| and 22 constituting one pair ofsections are connected to each other at their outer ends, remote fromthe header 20, by bending the ends angularly toward each other asindicated at 46, and welding them to each .other at the joint 41, sothat where the two sections meet they make an acute angle bend, changingthe direction of flow abruptly by substantially more than ninetydegrees. Thus any concentrated masses of liquid passing through thetubes or conduit sections at relatively high velocity are broken up intoa spray, or somewhat atomized when they hit these sharp angular comers.Moreover, the sharp angle presented exteriorly of the tubes reduces theresistance to flow of surrounding liquid in a direction along the tubes.

The tubes extend substantially parallel to each other throughout themajor portions of their length, as shown in Fig. 3, and their endsopposite'to the header 2!! are supported by posts welded or otherwisesuitably secured to the tubes, and connecting each tube of one pair ,orpass to the-adjacent tube ofthe next pair or pass. These posts 50 are ofsmall cross section and relatively flexible, so that expansion orcontraction of the'tubes caused by differences in temperature willsimply bend the posts 50 without distorting the tuhes themselves. A.post 5| secured to the tank wall l3 and extending inwardly therefrom isconnected to one of the members 50, as shown especially in Figs; 3 and4, to support one end of the tube assembly or cooling 'unit in spacedrelation to the tank. This post 5| is relatively broad in a. directiontransverse to the length of the cooling unit, as seen from Fig. 4,

so as to have substantial resistance to deformation in this direction.In the direction of the length of the cooling unit, however, the post 5|is relatively thin as seen from Fig. 3, so that it offers onlyslightresistance to bending by forces exerted in a direction lengthwiseof the cooling unit. Thus expansion and contraction of the cooling unitin a lengthwise direction does not damage the unit or the tank, sincethe post 5| simply bends to accommodate the relative movement betweenthe tank and the end of the cooling unit.

The opposite ends of the tubes or conduit sections 2| to 34, inclusive,or left hand ends when viewed as in Figs. 3 and '7, may be joined to theheader 20 in any suitable manner. Preferably all of the tubes 2| to 34are of the same external diameter, and the header 20 is formed of a tubehaving an internal diameter substantially equal to the external diameterof the tubes. The ends of the tubes 2| to 34 extend through openings inthe header tube 201 and project into the header, and are cut obliquelyat approximately forty-five degrees, so that they form partitions in theheader as shown. The tubes are preferably welded to the header wherethey enter it.

An inlet conduit and an outlet conduit 56 extend from the header, atpoints on opposite sides -of the partition 4|, out through a smallopening in the end wall of the tank l3. A plate 58, surrounding theconduits 55 and 56 and welded to them to form a fluid tight jointtherewith, forms a closure for the tank opening and a support forsupporting the inlet and outlet conduits which, in turn, form thesupport for the header 20 and its end of the whole cooling unit. Twoplates 59 are fitted around the conduits 55 and 56 externally of thetank, and bolts connected to the plate 58 extend through the plates 59and have nuts bearing against the plates 59, to draw the plate 58 firmlyinto fluidtight engagement with the tank. A volatile or low-boilingrefrigerating liquid of any suitable kind, such as ammonia,methylchloride, sulphur dioxide, Freon, etc., is supplied to the inletconduit 55 through a conduit 60 (Fig. 1), and after flowing through thecooling unit, the refrigerant, now mainly avapor, but possibly includingsome liquid, comes out through the outlet conduit 56 and its externaloutlet connection 62.

Any number of tubes or conduit sections may be employed, to provide any.number of loops or passes in the cooling unit, depending upon therequired cooling capacity and other characteristics desired. The inletand outlet connections may be at any desired points with respect to theseveral tubes. In the embodiment here illustrated as a preferred exampleof the invention, fourteen tubes or conduit sections are employed,connected in pairs to provide seven loops or passes. Each tube ispreferably straight, except for the bend at at one end where it isconnected to the other tube of the same pair, and the tubes are allsubstantially parallel to each other and to the axis of the tank, whichis substantially horizontal. In the preferred. example, the inlet andoutlet are near the low point of the elliptical header 20, and so placedthat the refrigerant flows up hill through about the first three oops.and downwardly through the remainder of theloops intervening headerportions, then flows and intervening header portions, to the outlet.

It will be readily seen from Fig. '7 that the ends of the tubes whichproject into the header 20 form partitions therein in such manner asthereof, then back through the tube 22 to the header, then along theheader a short distance to the open end of the tube 23, along this tubeto the remote end thereof, back to the header through the tube 24, andso on, passing successively through the tubes 25 to 34, inclusive, inthe direction of the arrows in Fig. 7, finally emerging from the headerthrough the outlet 56.

Preferably an agitator 10 (Figs. 3 and 4), of the impeller or propellertype is mounted within the tank l3 on a shaft H extending through theend wall of the tank remote from the header 20, and is driven by asuitable motor and gearing within the housing 12. In the preferred form,the shaft H is alined substantially with the long axis of the coolingunit through the center of the elliptical cross section thereof, so thatwhen the agitator is in operation it tends to force a stream of theliquid within the tank lengthwise through the cooling unit. The coolingunit offers only slight resistance to the flow of the liquid in thisdirection, since the flow is lengthwise of the tubesnot across them, andthis resistance is still further reduced if the sharp angularconnections 46, 41 between the two tubes of each pass are used, asindicated in Figs. 3-

and 5, rather than the return bends of Fig. 6. Hence extremelysatisfactory and rapid cooling results from this arrangement, with theexpenditure of a relatively low amount of power for agitation.

The elliptical outline of the header 20 is preferably slightly smallerthan the similar elliptical outline of the manhole l1. At no point doany of the tubes 2| to 34, inclusive, as a group have any crosssectional outline larger than the elliptical outline of the header 20.Hence the entire tube assembly and header may be inserted endwise intothe tank in completely assembled condition throughthe standard manholeI1. After the unit is inserted, it is placed in proper position with theinlet and outlet connections 55 and 56 extending through the smallconnection hole in the tank, and with the plate 58, which has beenpreviously welded to the connections 55 and 56, in position to closethis opening, as shown in Fig. 2. Then the outer plates 59 are put inposition at the outer end of the connection hole, and the nuts areapplied to and tightened on the bolts previously secured to the plate58. The supporting post 5| is connected to the cooling unit to supportthe end thereof remote from the header 20, and the necessary conduitconnections are made, externally of the tank, to the inlet and outlet ofthe unit, and this completes the installation of the cooling apparatus.It is seen that only aslight amount of work is required within the tank,and no parts whatever have to be assembled within the tank except theconnection of the supporting post 5| to the tank and to the coolingunit, all other assembling operations being done exteriorly of the tank.

Another feature of the present invention is that the cooling unit is notmounted directly along the center line of the tank, but is mounted alittle to one side of a vertical plane passing through the longitudinalaxis of the tank, as indicated in Fig. 1. Hence, when it is necessary toclean the interior of the tank and the exterior of the cooling unit, aman may enter the tank, and may stand directly on the lowest part of thebottom thereof at the point where this bottom is approximately level,instead of being forced to stand on the more sloping part of the bottom,to one side of the central plane, as would be the case if the coolingunit were mounted directly along the central plane. Moreover, the tubes28 and 29 are preferably spaced from each other a little farther apartthan the other tubes, as indicated in Figs. 1, 4, and 8, to allow ampleroom between those tubes so that a person standing within the tank mayinsert a brush or other suitable implement through the space betweenthese tubes to clean those sides of the tubes which are faced toward thecenter of the elliptical assembly.

Another important feature of the present invention is the interiorconstruction of the tubes or conduits of the cooling unit. In coolingunits of the type which obtain the cooling effect by boiling orvolatilizing a liquid refrigerant, it has heretofore been generallybelieved that there should be only a very slight difference between theinlet pressure and the outlet pressure in order to obtain greatestefliciency. According to the present invention, however, greaterefficiency may be attained if greater pressure differences are used, andif the internal construction of the passageway, tubes, or conduits issuch that the refrigerant passes through them with relatively highvelocity and keeps the inner surfaces of the tubes or passagewayssubstantially completely or very largely covered by a film ofunvaporized refrigerant in liquid phase. It is highly desirable to haverelatively high velocity of flow even at or near the inlet end of thecooling unit. Yet, if the tubes forming the passageway or conduit bemade sufficiently small to obtain the desired velocity of flow in thefirst part of the cooling unit, it is apparent that, with theconventional construction, tubes of the same size would be much toosmall at a further advanced point in the cooling unit, where the volumeof refrigerant was much greater due to passage of a portion thereof fromliquid phase to vapor phase. As formation of vapor continues, and thevolume of the refrigerant very greatly increases, the velocity of flowwould rise to excessive heights, if the cross sectional size of thepassageway remained constant. Or, if the tubes were made large enough toaccommodate the required volume of refrigerant at the outlet end of theunit, tubes of this same size would be much too large near the inlet endof the unit, resulting in sluggish and inefficient flow in this part ofthe unit.

One way of overcoming this difficulty, according to the presentinvention, is to provide successive tube sections of increasing size.Such an arrangement is not preferred under most circumstances, however,,.because usually it is desirable to have the various tubes of thecooling unit all of the same or approximately the same externaldiameter.

Hence, according to the preferred form of the present invention, thefirst few tubes are provided with what may be termed fillers inside thetubes, to reduce the cross sectional area of the passageway areaavailable for flow of the refrigerant. For example, the two tubes 2| and22 of the first pass or loop are provided with rods 8| of an externaldiameter slightly smaller than the internal diameter of these tubes. Thenext two tubes 23 and 24 constituting the second pass, are provided withrods 82 slightly smaller than the rods 8| so that a somewhat greatercross sectional area is available for flow of the refrigerant. Thedesired tapering effect, or increasing cross section of flow passageway,may be obtained even more smoothly and satisfactorily by winding theserods 8! and 82 with spirally arranged wires of gradually increasingpitch. Around the rod 8| in the tube 2| is wound a wire, 85 of such sizethat it touches, or substantially touches, the inner wall of the tube2|; Thus the refrigerant cannot flow directly along the tube, but mustflow spirally around and around the annular space between the rod andthe tube, along the passageway defined by the wire. As shown plainly inFig. I, the wire starts off with a relatively small pitch, and thispitch gradually increases throughout the length of the rod 81, so thatthe cross sectional area of the passageway defined by the wire graduallyincreases throughout the length of this tube. Similarly, a wire 86 woundaround the rod 8! of the tube 22 starts with a pitch about equal to thefinal pitch of the wire 85 at the discharge end of the tube 2|, and thewire 86 gradually increases in pitch in the direction of flow, so thatthe cross sectional area of the flow passageway is gradually increasedthroughout the length of the second tube 22.

In the third tube 23, since the rod 82 is smaller, a larger wire 81isused in order to fill the space between the rod and the tube. Thiswire Bl starts out with a relatively small pitch as shown in thedrawings, which pitch gradually increases in the direction of-flow. Thewire 88 around the rod 82 in the tube 24 likewise has a pitch increasingin thedirection of flow.

The wires 85, 86, 81, and 88 may be welded either continuously or atspaced intervals to the rods on which they are wound, before the rodsare inserted in' the ends of the tubes. Then the rods with the wireswound on them are put in the ends of the tubes before the tubes are setinto and welded to the header 28.

v This same construction, using smaller and smaller rods in thesuccessive loops or passes, and

wires of increasing pitch wound around the rods in each loop, may beused throughout all or any desired number ofthe loops or passes. If usedthroughout substantially all of the. loops, however, this constructionwould usually result in tubes of undesirably large diameter, whereas itis usually preferred to employ tubes of relatively small diameter, whichare much less expensive, especially when made of high priced materialssuch as stainless steel. Hence, in the preferred embodiment, the rod andspiral wire construction is employed only in the first two loops orpasses of a total of seven loops, and a different construction isprovided in the remaining loops.

The tubes 25 and 26 of the third pass or loop are preferably providedwith deflecting means or baffle means to give the fiuid a somewhatswirling or rotary action within the tubes as it flows along them, butwithout substantially decreasing the cross sectional area of the fiowpassageway. This baflle means or deflecting means is preferably in theform of a wire or small rod 90 wound spirally or helically and lyingagainst the inner surface of the tube or conduit, to form, in effect, aspiral or helical ridge or fin projecting inwardly from'the innersurface. fin does not substantially decrease the available crosssectional area for flow of fluid through the tube, but it does offerjust enough resistance to the flow of the fluid so that the fluid iscaused to rotate or swirl in a spiral manner as it flows longitudinallythrough the conduit. Thus, as the refrigerant flows through the conduit,that part of the refrigerant which is in vapor phase,

This ridge or swirling around and around the inner circumference of theconduit, carries along with it that part of the refrigerant which is inliquid phase, keeping substantially the entire inner surface of theconduit coated with a film of liquid at all times. Were this deflectingbafile means not provided, the liquid refrigerant might run along thebottom part of the tube or conduit and only gas or vapor withsubstantially no liquid might be in contact with the upper part of thewalls of the tube, with consequent reduction in efiiciency.

The deflecting or baffle means might also be in the form of a strip ofsheet metal or the like twisted spirally and placed within the tube orconduit, such spirally twisted strips being indicated in the alternativeconstruction shown in Fig. 9 of the drawings. Usually, however, it ispreferred to use a spirally extending wire or small rod, rather than aspirally twisted strip, because the wire or rod does not reduce thecross sectional area of the conduit to quite so great an extent, anddoes not increase the frictional resistance to flow to quite such anextent.

All of the tubes 25 to 34 inclusive of the remaining passes arepreferably provided with spirally or helically arranged baflle ordeflecting means such as above described, preferably in the form of theabove mentioned spiral wire or small rod, although some may be of thespirally twisted strip form and others may be of wire or small rod form,if desired. For instance, if it is preferred to reduce the crosssectional area of the conduits of the third pass to some extent, but notto so great an extent as by the use of a filler rod 82, then the tubesor conduits of the third pass could be provided with the .spirallytwisted strips abovev mentioned, while the conduits or tubes of thefourth and succeeding flow substantially slower through the first partof the conduit 25 than through the conduit 24, gradually increasing itsrate of flow through the conduits 25 and 26 asadditional liquid boilsaway and forms an increased volume of vapor. At the end of the thirdpass, that is, at the left hand end of the tube 26 when viewed as inFig. '7, the velocity of flow has preferably been brought up to aboutthe velocity obtaining at the end of the tube 24. The velocity of flowwill be further increased in the next or fourth pass made up of theconduits-21 and 28, and in each succeeding pass, due to boiling off ofadditional refrigerant from liquid phase to vapor phase, unless means isprovided for counteracting this tendencyj 0f the velocity to increase.Such means may or-may not be provided, depending on the results'desired.When such means is desired, it mayltake the place of by-pass openingsacross the ends of the passes so that more or less of the refrigerantwill be bypassed along the header 28 instead of flowing through the fulllength of each pass.

Such bypass openings across'the fourth loop or pass formed of the tubes21 and 28, are shown at 93 in Fig. '7. These openings 93 are formed,

in the partition-like ends of the tubes 21 and 28 within the header 28,so that part of the refrigtube 21, thence a short distance along theheader 28, and through the opening 93 in the next tube erant may passthrough the opening 93 in the respective passes.

28, to meet the other portion of refrigerant which has flowed around thefull length of the pass Similar by-pass openings 95 may be formed in thetubes 29 and 30 of the fifth pass, and similar openings 91 may be formedin the ends of the tube 3| and 32 of the sixth pass.

The sizes of the respective by-pass openings will depend upon theconditions desired. If it is preferred to have the velocities of flow atthe ends of the fourth, fifth, and sixth passes approximately equal toeach other and approximately equal to the velocity of flow at the end ofthe third pass, then the respective by-pass openings 93, 95, and 91should be of such sizes as to by-pass just enough of the refrigerant tocompensate for the increasing volume of refrigerant through these If itis desired to have the velocity of flow decrease progressively, so thatit is slower at the end of the sixth pass than at the end of the fifth,and slower'at the end of the fifth than at the end of the fourth, etc.,then the by-pass openings would be still larger than the sizes requiredto compensate for the increasing volumes of refrigerant. Such a decreasein velocity from one pass to another is seldom desired.

If it is desired to have the velocity of flow increase somewhat from theend of one pass to the end of the next, so that at the end of the fourthpass the velocity is greater than at the end of the third pass, and atthe end of the fifth pass greater than at the end of the fourth, etc.,then the by-, pass openings either would be omitted entirely, as isfrequently permissible, especially in small cooling units, or would bemade somewhat smaller than the size required to compensate fully for theincreasing volume of refrigerant. The judgment of the designingengineer, rather than any set rule or formula, should be the guide indetermining whether or not to use any by-passes, and in determining thesizes of the by-passes to be used. If by-passes are used, thedetermination of the sizes of the by-pass openings must take intoaccount the greater friction caused by flow throughout the entire lengthof one pass or loop, than the friction of flow through the much shorterby-pass path across the end of the pass or loop.

With a cooling unit having passes or loops of one certain size andlength, it is found that bypass openings having a cross sectional areaabout 15% of the total cross sectional area of the pass or loop willapproximately compensate for the increase in velocity which wouldotherwise be caused by boiling off of refrigerant within that pass orloop. With this particular size of pass, the by-pass openings 93 mighthave an area of about 15% of the area of the tubes 21 and 28, theby-pass openings 95 might have an area of about 30% of such tube area,and the by-pass openings 91 might have an area of about 45% of such tubearea, and the velocity of flow in the latter part of the tube 32, justbefore reaching the header 2!), would then be about equal to thevelocity of flow at the end of the tube 26. These same areas of by-passopenings would give difierent results, however, with tubes of differentlength or characteristics, and hence they must be taken merely as anillustration of one particular embodiment of the invention, rather thanas a limitation or as a definite guide for constructing other,embodiments.

By-pass openings 99 may also be provided, if

desired, through the ends of the tubes 33 and 34,

constituting the last or seventh pass or loop. The sizes of theseby-pass openings would again depend upon the judgment of the designingengineer and the results which he wishes to obtain. Frequently it ispreferred to use no by-pass at all across the last loop, even throughby-passes may be used across some of the preceding loops, because aby-pass across the last loop will frequently allow some liquidrefrigerant to pass through this by-pass, so that the refrigerant willnot be completely vaporized in the unit. Greater efliciency ofvaporation would be attained, therefore, by using no by-pass across thelast loop. But this greater efficiency of vaporation would be at theexpense of perhaps slightly less efiiciency of cooling, because therewould be greater back pressure if no by-pass were provided, withconsequent slower velocity of flow through the unit. Frequently it isdesirable to use a relatively small by-pass across the last loop orpass, smaller than the size which would theoretically be used at thispoint, in order to increase somewhat the rate of flow without lettingtoo much liquid refrigerant pass through the by-pass. If no by-pass isused,

practically all of the remaining liquid refrigerant I will usually bevaporized in the last pass.

With the foregoing construction a highly satisfactory cooling unit isprovided. The high rate of flow in comparison to the very sluggish flowof refrigerant through conventional cooling units greatly increases thecooling capacity by raising the rate at which heat may be transferredthrough the conduit or tube walls to the refrigerant. A high rate offlow has the further and important advantage that the liquid refrigerantis carried along with the gas or vapor by reason of the rapid movementof the latter so that the liquid does not form concentrated masses norremain stagnant in the lowest part of the system, but is positivelyforced or carried along at all times.

If any oil becomes mixed with the refrigerant, it

does not collect and remain in the system, blanking off the heatexchanging area thereof and reducing the efiiciency of the cooler, butthe oil, like the liquid refrigerant, is carried along through theapparatus by the rapid flow of gas or vapor.

Due to. the spiral or helical construction, both around the filler rods8| and 82 and around the inner surfaces of those conduits or tubes whichdo not have filler rods, the rapidly flowing gas swirls around in suchmanner that the liquid refrigerant is constantly carried over the entireinner surface of the tubes, at the top sides as well as bottom sidesthereof, so that a layer of liquid refrigerant coats substantially theentire inner surface of the tubes at all times, promoting a maximumdegree of cooling. The spiral or swirling action helps to keep theliquid broken up into more or less of a spray of small particles, but ifany substantial masses or concentrations of the liquid should form,notwithstanding the swirling action, these bodies of liquid would bequickly broken up into a spray, or into much smaller bodies, by thesharp corners or bends with which they would come into violent contact.The sharp corners formed at the junction of the two tubes at their endsremote from the header are particerably about 400 feet per minute, inthe first tube of the first pass or loop, and this should be raised to avapor speed of not less than about 2000 feet per minute and preferably aspeed of about 3600' feet per minute at the end of the last tube of thelast loop.

As previously stated, the inlet and outlet connections of the header 2dare arranged so that through about the first three loops or passes therefrigerant flows in an uphill direction, and thereafter the refrigerantfiows in a downhill direction. This is advantageous because, with thisarrangement, some of the unvaporized or liquid refrigerant will beconstantly running for ward through the by-passes 93, t5, and $7 tosupply adequate liquid refrigerant to the last few passes.

The outlet of the cooling unit is preferably connected to a backpressure valve set for a pressure of about forty-five pounds to thesquare inch. The inlet is provided with either a hand.

operated or automatically operated inlet valve arranged to give maximumcooling capacity. Usually the refrigerant will be supplied under apressure of, say ninety to one hundred and fifty pounds to the squareinch. The above mentioned pressures and velocities are those found mostsatisfactory when ammonia is used as the refrigerant, and somereadjustment of pressures and velocities may be desirable if othervolatile refrigerants are used, such as methylchloride, sulphur dioxide,Freon, etc.

The preferred embodiment illustrated by way of example in Figs. 1 to 8,inclusive, is an embodiment in which the cooling unit is intended to beimmersed in the milk, water, or other-liquid which is to be cooled. Aspreviously stated,

the principles of the present invention may be applied equally well to acooler of the surface type rather than the immersion type, and such asurface cooler may be of the form illustrated by way of example in Fig.9. Here, two substantially vertical headers III and H2 are employed. Anydesired number of tubes or conduits may be used, twelve being hereshown, numbered from I2I to I32 inclusive. Each of these tubes extendsap proximately horizontally and has one end connected to one header andthe other end connected to the other header. As in the previousembodiment, the connection may conveniently be made by providing holesin the headers of the proper size to receive the tubes, the exteriordiameters of the tubes being approximately equal to the internaldiameters of the headers. The ends of the tubes projecting into theheaders, are cut diagonally, as shown, so that these prpjecting ends ofthe tubes form partitions in the headers.

The refrigerant may pass through the various tubes in any desired order,but preferably starts at a tube somewhatbelow the top of theunit, flowsupwardly to the top, and then downwardly through the remaining tubes.For example, the inlet I40 may enter the header III near the end of thetube I2 I, which is the fourth tube from the top. A partition I II inthe header III just below the inlet prevents the refrigerant fromescaping downwardly in the header, while the end of the tube I2I itselfforms a partition preventing the refrigerant from escaping upwardly.Hence the refrigerant must flow into and through the tube I2I. From theright hand end of the tube I2I, when viewed as in Fig. 9, therefrigerant flows into the header II2, up this header a short distanceinto the right hand end of the tube I22, then leftwardly along the tubeI22 to the header l I I, upwardly through this header to the left handend of the tube E23, and along this tube I23 to the header H2. Here, therefrigerant again passes upwardly through a short section of the headerl I2, enters the right hand end of the top tube I2d, and flowsleftwardly through it, this time not to the header Hi, but to the end ofa conduit it which conveys the refrigerant downwardly to a point in theheader Hi just below the'partition Iti. Here, the refrigerant enters theend of the tube H25, which is the next tube below the tube H25. Then therefrigerant flows through the tube E25 to the header 5 it, down throughthis header to the next tube I26, leftwardly through the tube I26 to theheader Hi, and so on successively through the tubes l2? to 932, finallyissuing from the left hand end of the tube E32 into the bottom of theheader I I I, and then into the outlet connection M91 This outletconnection is provided with a suitable back pressure valve use and theinlet connection Mil is provided with an inlet valve I55 which may becontrolled automatically by' a temperature control including the heatresponsive element 855 adjacent the outlet M8.

The interior construction of the tubes in this form. of cooler may bethe same, or substantially the same as that previously described'inconnection with the previous embodiment. For example, the first twotubes I2I and I22 may both be provided with filler rods 56$ around whichwires it! and I62 are wound spirally or helically, with graduallyincreasing pitch, in a manner similar to the wires 85 and 86 in theprevious embodiment. The next twd tubes I 23 and I24 may be providedwith smaller filler. rods I84, wound with larger wires 565 and I66 ofgradually increasing pitch similar to the wires 81 and 88 previouslydescribed. The other tubes I25 to I32, inclusive,

may omit the filler rods, but preferably are provided with baffle meansor deflecting means for causing spiral or rotary swirling of therefrigerant passing through these tubes. This baflle or deflecting meansmay be in the form of a spirally wound wire or small rod like the wiresor rods 90 in the previous embodiment, or may be in the form of spirallytwisted strips IIII.

As before, by-pass means may or may not be employed, according to thejudgment of the designing engineer. If by-passes are desired, there maybe a by-pass "2 between the tubes I21 and :28, and a by-pass I14 betweenthe tubes I28 and The milk, water, or other liquid to be cooled may becaused to flow over all or any suitable part of the surface of the tubesI2I to I22 inclusive. For instance, a tank or hopper may dischargeliquid onto the top of the uppermost tube I24, and after the liquid hasflowed down the sides of the tube a fin I depending from the bottom edgeof the tube may direct the liquid onto the top of the next lower tubeI23. Similar fins I80 may beprovided on the bottom edges of each of thetubes so that the liquid to be cooled flows in succession from each tubedown its fin into the top of the tube below, the cooled liquid finallybeing caught in a suitable receptacle or trough beneath the bottom ofthe last tube I22.

This surface type of cooling unit may be either open or enclosed in asuitable housing. Its internal operation is substantially the same asthat previously described in connecticz with the first the inventiveidea may be carried out in a number of ways. This application istherefore not to be limited to the precise details described, but isintended to cover all variations and modifications thereof fallingwithin the spirit of the invention or the scope of the appended claims.

I claim:

1. Refrigerating apparatus comprising conduit means forming a passagewayfor flow of a refrigerating agent having a tendency to pass from liquidphase to gaseous phase as heat is absorbed, said passageway havingfiller means therein of less cross sectional area than the area of saidpassageway, deflecting means arranged generally spirally around saidfiller means, and means for supplying a refrigerating agent at leastpartially in liquid phase to said passageway at one end thereof at apressure substantially higher than that existing at the other end ofsaid passageway so that said refrigerating agent will flow rapidly alongsaid passageway and that part thereof which remains in liquid phase willbe deflected during its flow, by said deflecting means, so as to spreadover substantially the entire perimeter of said passageway.

2. Refrigerating apparatus for use with a refrigerating agent having atendency to pass from liquid phase to gaseous phase as heat is absorbed,said apparatus comprising means forming a circuitous passageway having aplurality of convolutions through which said refrigerating agent flows,means for supplying said refrigerating agent at least partly in liquidphase to one end of said passageway at a pressure sufiiciently higherthan that existing at the other end of said passageway so that saidagent will flow relatively rapidly through said passageway. and by-passmeans of restricted cross sectional area for bypassing a portion of saidrefrigerating agent in liquid phase past one of said convolutions sothat it may be effective to pass into vapor phase and absorb heat in asubsequent convolution.

3. Refrigerating apparatus for use with a refrigerating agent having atendency to pass from liquid phase to gaseous phase as heat is absorbed,said apparatus comprising means forming a circuitous passageway having aplurality of convolutions through which said refrigerating agent flows,means for supplying refrigerating agent at least partly 'in liquid phaseto one end of said passageway at a pressure sufficiently higher thanthat existing at the other end of said passagewav so that said agentwill flow relatively rapidly through said passageway, by-pass means ofone cross sectional area for by-passing a portion of said refrigeratingagent partly in liquid phase past one of said convolutions. and by-passmeans of a substantially different cross sectional area for by-passing aportion of said refrigating agent partly in liquid phase past another ofsaid convolutions so that the portion of the by-passed agent which is inliquid phase may-be effective to pass into vapor phase and absorb'heatin a subsequent convolution beyond the one past which it is bypassed. IY

4. The combination with a liquid container, of conduit means within saidcontainer for carrying fluid in heat exchanging relationship to liquidin said container, said conduit means including a plurality of sectionsarranged approximately parallel to each other and grouped around acentral free space, and propeller agitating means within said containerand beyond one end of said grouped sections and approximately alinedwith said central free space to tend to drive liquid within saidcontainer in a general direction through said free space and along saidconduit sections.

5. The combination with a container, of an serving also to support oneend of said coil, and

supporting bracket means adjacent the opposite end of said coil fromsaid header means and connecting said opposite end of said coil to awall of said container to support said opposite end 0f said coil, saidbracket means being relatively flexible in a direction lengthwise ofsaid coil and relatively inflexible in a direction transversely of saidcoil.

6. The combination with a container having an approximately cylindricalportion arranged with its axis approximately horizontal, of elongatedcoil means mounted within said container adjacent the bottom thereof andwith the long dimension of said coil means extending approximatelyparallel to said axis, said coil means being formed of a plurality ofconduit sections extending approximately parallel to each other through.the major portion of the length of said coil means and grouped around acentral free space, at least two of said conduit sections beinglaterally spaced sufficiently far from each other so that lateral accessmay be readily obtained to said central space for cleaning thoseexterior surfaces of said conduit sections which are faced toward saidcentral space, said coil means being offset laterally from a verticalplane passing through said axis so that a person may, withoutsubstantial interference from said coil means, stand within saidcontainer at the lowest point of the bottom thereof to clean saidcontainer or said coil means.

7. Cooling means comprising a series of conduit sections extendingsubstantially horizontally and arranged one above another in asubstantially vertical plane, means for supplying a cooling agent to oneend of one of said sections at an intermediate height in the series ofsections, means connecting that section to the sections above it so thatthe supplied cooling agent flows successively through that section andthe sections above it to the topmost section, means connecting thedischarge end of the topmost section to one end of the section nextbeneath the one to which the cooling agent was initially supplied, andmeans for connecting said next beneath section to the sections below it"so that said cooling agent will flow from said topmost section to saidsection next beneath the one to which the coolvaporization point at thepressure of the inletv end, said conduit having a substantially uniformexternal size throughout a portion of its length, means in said conduitcooperating with the walls thereof to form a channel of across-sectional area increasing in the-direction of flow throughout saidsame portion of the length of the conduit, and means for flowing therefrigerant through the conduit at high velocity throughoutsubstantially its entire length.

9. In refrigerating apparatus wherein a refrigerant is circulatedthrough a refrigeration circuit having a high pressure and low pressureside, a conduit constituting part of the low pressure side of saidcircuit into which the refrigerant is 1 passed from the high pressureside, means for vaporizing a portion of the refrigerant adjacent theinlet end of the conduit to cool the refrigerant in liquid phase downsubstantially to the vaporization point at the pressure of the inletend, said conduit having a substantially uniform external sizethroughout a portion of its length, means in said conduit cooperatingwith the walls thereof to form a channel of a cross-sectional areaincreasing in the direction of flow throughout said same portion of thelength of the conduit, means for flowing the refrigerant through theconduit at high velocity throughout substantially its entire length, andmeans in said conduit for v causing the refrigerant to flow therethroughin intimate contact with substantially the entire inner wall thereofthroughout said same portion of the length of the conduit.

10. In refrigerating apparatus wherein a refrigerant is circulatedthrough a refrigeration circuit having a high pressure and low pressureside, a conduit constituting part of the low pressure side of saidcircuit into which the refrigerant is passed from the high pressureside, means for vaporizing a portion of the refrigerant adjacent theinlet end of the conduit to cool the refrigerant in liquid phase downsubstantially to the vaporization point at the pressure of the inletend, said conduit having a substantially uniform external sizethroughout a portion of its length, means in said conduit cooperatingwith the walls thereof to form a channel of a crosssectional areaincreasing in the direction of fiow throughout said same portion of thelength of the conduit, means for flowing the refrigerant through theconduit at high velocity throughout substantially its entire length, andmeans in said conduit for causing the refrigerant in liquid phase toflow through said same portion of the length of the conduit with awhirling motion in intimate contact with substantially the entire innerwall thereof. i

11. In refrigerating apparatus wherein a refrigerant is circulatedthrough a refrigeration circuit having a high pressure and a lowpressure side, a conduit constituting part of the low pressure side ofsaid circuit into which the refrigerant is passed from the high pressureside, means for vaporizing a portion of the refrigerant adjacent theinlet end of the conduit to cool the refrigerant in liquid phase downsubstantially to the vaporization point at the pressure of the inletend, said conduit having two tubular portions through which therefrigerant successively flows, both of said portions being of the samecross-sectional dimensions, filler means of substantially differentcross-sectional dimensions within said two portions cooperating with thewalls thereof to form channels, the filler means in the second portionbeing of substantially smaller cross-sectional dimensions than thefiller means of the first portion to allow a larger crosssectional spacefor flow of said refrigerant through said second portion than throughsaid first portion, deflecting means extending generally spirally aroundthe fillermeans in at least one flow of a cooling agent therethrough,said coil including a generally ring-shaped header tube having a seriesof openings therein, a series of tubes extending laterally with respectto said header tube and being approximately parallel to each other andgrouped around a central free space, each of said tubes having an endextending into said header tube through one of said openings and forminga substantially fluid tight connection with said header tube around theopening through which the tube extends, and means operatively connectingsaid tubes to each other in pairs at points remote from said headertube.

13. The method of operating a refrigerating system having a section of acooling coil, said method including the steps of maintaining therefrigerant under a substantial pressure to maintain the refrigerant inliquid phase, passing the refrigerant into said coil section with anappreciable drop in pressure to thereby vaporize a portion of therefrigerant and cool the refrigerant in liquid phase to substantiallyits vaporization point at the pressure of the inlet end of the coilsection, restricting the cross-sectional area of the stream of therefrigerant at the inlet end of the coil section so that a relativelyrapid rate of flow is maintained at said inlet end to thereby avoidstagnant pools of refrigerant adjacent said inlet end, maintaining sucha high rate of flow of refrigerant throughout the coil section as toprevent the formation of stagnant pools of liquid refrigerant therein,causing the liquid component of the stream to flow through a largeportion of the coil section in contact with substantially the fullcircumference of the inner wall of such portion, and increasing thecross-sectional area of the stream substantially uniformly andprogressively in the directional flow throughout a substantial length ofsaid section as the volume of refrigerant in vapor phase increases.

14. The method of operating a refrigerating system having a section of acooling coil, said method including the steps of maintaining therefrigerant under a substantial pressure to maintain the refrigerant inliquid phase, passing the refrigerant into said coil section with anappre ciable drop in pressure to thereby vaporize a portion of therefrigerant and cool the refrigerant in liquid phase to substantiallyits vaporization point at the pressure of the inlet end of the coilsection, maintaining such a high rate of flow of refrigerant throughoutthe coil section as to prevent the formation of stagnant pools of liquidrefrigerant therein,"causing the liquid stream of refrigerant to flowthrough at least a portion of the coil section at said high rate with awhirling motion so that the portion of the stream of refrigerant inliquid phase is maintained adjacent substantially the fullcircumferenceof the inner side walls of the .coil in intimate contacttherewith by centrifugal action, and increasing the cross-sectional areaof the stream substantially uniformly and progressively in thedirectional flow throughout a substantial length of said section as thevolume of refrigerant in vapor phase increases.

OTTO W. GREENE.

